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September 1, 2005

C-section linked to cavity-causing bug in infants

by Sam Savage

By Amy Norton

NEW YORK (Reuters Health) - Some infants delivered by
cesarean section may have a higher risk of developing cavities
later in life, a new study suggests.

Researchers found that among young children who harbored a
particular cavity-causing bacterium in their mouths, those who
were delivered by C-section acquired the infection one year
earlier, on average, than those delivered vaginally. Mothers
appeared to be the main source of transmission of the
bacterium, known as Streptococcus mutans.

Since early acquisition of S. mutans, which can make cavity
development more likely, the findings suggest that these
children could be at greater risk of cavities down the road.

That's not certain, since the study did not follow the
children long enough, lead study author Dr. Yihong Li told
Reuters Health.

Still, she said the "take-home message" is that women with
cavities who deliver by C-section should pay particularly close
attention to their children's oral health over time.

Li, an associate professor at the New York University
College of Dentistry, and her colleagues report the findings in
the Journal of Dental Research.

The researchers suspect that vaginal delivery offers
infants some early protection against S. mutans colonization.
Passing through the birth canal exposes newborns to "good
bacteria" from their mothers that are key to setting up
infants' defense against disease-causing bugs. These beneficial
bacteria set up colonies that leave little space for less
benign sorts like S. mutans.

But because C-section deliveries are relatively aseptic,
these infants may be more vulnerable to early S. mutans
colonization, Li explained.

For their study, she and her colleagues followed 156 mainly
African-American mothers and their infants for 4 years. All of
the women were low-income and three quarters had cavities.

Overall, the researchers detected S. mutans in 35 percent
of the children over the study period. Those who were delivered
by C-section first showed the bacterium at the age of 17.1
months, on average, versus 28.8 months among children who were
delivered vaginally.

The age gap is important, Li said, because other research
has suggested that earlier S. mutans acquisition increases a
child's cavity risk.

But "mode of delivery" was only one of the variables that
affected a child's acquisition of S. mutans, Li pointed out.
Among the other factors were the extent of a mother's tooth
decay and the level of S. mutans in her saliva.

The study adds to recent research that has highlighted the
potential importance of a mother's oral health to her child.
Several studies, for example, have linked maternal gum disease,
which is caused by bacteria, to poorer fetal growth and a
higher risk of preterm delivery and certain other pregnancy
complications.